Researchers Sequence Horse Genome

Posted November 09, 2009

COLLEGE STATION, TX - A group of international
scientists - including three researchers from Texas A&M
University -- have completed for the first time the genome sequence
of the horse, which may open doors for improved breeding, disease
treatment and even enhanced performance traits.

Dr. Loren Skow (left), Dr. Terje Raudsepp and Dr. Bhanu
Chowdhary participated in the project to sequence the participated
in the horse genome.

The multi-national team of 60 researchers has published its work
on the project in the current issue of "Science" magazine. Funding
groups include the National Human Genome Research Institute, the
Dorothy Russell Havemeyer Foundation, the Volkswagen Foundation,
the Morris Animal Foundation and the European Science
Foundation.

Texas A&M researchers Loren Skow, Bhanu Chowdhary and Terje
Raudsepp, all associated with the College of Veterinary Medicine
& Biomedical Sciences, participated in the horse genome
project, completed at Broad Institute in Cambridge, Mass. The group
took DNA from a single Thoroughbred mare for the sequencing
project.

The researchers say that with more than 90 hereditary conditions
such as infertility, muscle disorders, allergies and inflammatory
diseases, sequencing the horse has much to offer as a model
species.

"One thing we learned from the project is that the structure of
the chromosomes in the horse is similar to other mammals, including
humans," Skow says.

"The information we collect from this will be helpful down the
road in work with genetic mutations and identifying certain
disorders, possibly even in developing strategies to increase
disease resistance."

Skow says that in general terms, horses and related donkeys and
zebras have chromosome structures that evolved rapidly compared to
other species. "This work gives us a chance to look closely at the
entire evolutionary process of chromosome formation and
diversification using the horse as a model," he adds.

"It also lets us look at the human-animal model closer at the
level of individual genes. If a gene has mutated in a horse, it may
help us identify a similar process and how it relates to a clinical
problem in humans. We may be able to point to that gene as the
problem and work from there. About one-half of the horse genome
sequence is very similar in organization to that of humans. So it
gives us a human application, but it can also work vice versa - it
may give us more knowledge about genetic problems in horses,
too."

The project has particular interest in Texas: the state is home
to more than 1 million horses, the most of any state, and the horse
industry has an economic impact of more than $5 billion, with
96,000 jobs directly related to the equine industry. About 300,000
Texans own at least one horse, studies show, and Texas leads the
nation in the number of registered American Quarter Horses,
American Paint Horses, Appaloosa Horses and American Miniature
Horses.

Chowdhary, associate dean for research and graduate studies in
the College of Veterinary Medicine & Biomedical Sciences and
one of the researchers involved in the project, notes that the
Texas A&M team "helped to provide the background map of the
horse genome.

"With the availability of the whole genome sequence, we have
entered into a new era in equine research. The sequence has already
led to the development of novel tools and resources that have
initiated studies previously considered difficult or
impossible.

"While the study of single traits or diseases will be
significantly enhanced, it will now be possible to study complex
traits governed by several genes, and perform association studies
between traits important to the industry and variations observed in
the genome."

Chowdhary adds, "Advanced analysis can now be initiated to
understand the molecular basis of disease resistance, reproduction,
fertility, etc. Studies have been initiated on the molecular basis
pathogenesis of important diseases. This reflects a major shift
that has been possible only due to the complete genome sequence of
the horse. There will definitely be more exciting research that
will follow soon."

Raudsepp says that completing the sequence "is exciting for what
it tells us about the equine genome now, and what it can tell us
years from now. We anticipate that the sequence assembly will
trigger the development of new tools to study the horse genome in
ways never envisioned earlier. It should significantly improve the
speed and accuracy to determine the underlying genetics of simple
and complex traits in horses.

"There is still a lot of work to be done, but this is a huge
step for the scientific community," she notes.